The observable universe is a big place that's been around for more than 13 billion years.
Up to two trillion galaxies made up of something like 20,000 billion billion stars surround our home galaxy.
In the Milky Way alone, scientists assume there are some 40 billion earth-like planets in the habitable zone of their stars.
When we look at these numbers, it's hard to imagine that there is nobody else out there.
It would change our perception of ourselves forever if we found others.
Just knowing that this vast place is not dead would shift our perspective outward, and could help us get over our irrelevant quarrels.
But before looking for our new best friends, or worst enemies, we have a problem to solve: What are we actually looking for?
But, we've only just started looking.
In a universe that big and old, we have to assume that civilizations start millions of years apart from eachother, and develop in different directions and speeds.
So not only are we looking over distances of dozens to hundreds of thousands of light years, we're looking for a civilization ranging from cavemen to super advanced.
